Solid oxide fuel cells (SOFCs) are designed to introduce reactant gases to two electrodes (i.e. an anode and a cathode) which are then brought into electrical contact via an electrolyte. Traditionally, the reactant gases are mixed within the fuel cell, with the oxidant, e.g. air, being first introduced at the cathodic portion of the fuel cell, and the fuel, e.g. hydrogen or hydrocarbon, being first introduced at the anodic portion. An external load is connected to the anode and cathode causing oxygen at the cathode to react with incoming electrons from the external circuit to form oxygen ions. The oxygen ions migrate to the anode through the electrolyte and oxidize the fuel at the anode, resulting in the liberation of electrons to the external circuit and causing a current flow that returns electrons to the cathode.
One development in SOFCs has been the use of a single chamber design to simplify the cell fabrication and subsequent system operation. The single chamber design requires the reactants to be mixed prior to delivery to the anode and cathode of the fuel cell. (See, for example, U.S. Pat. No. 4,248,941 to Louis et al.). Since SOFCs generally operate at or above 500° C., the potential for uncontrolled exothermic reactions is present in any single chamber design. Uncontrolled reactions can cause the consumption of the reactants before and during the delivery of the reactants to the operating cell resulting in reduced efficiency or potentially damaging explosions.